Copper-silver-beryllium-nickel alloy



Patented Jan. 17, 1939 UNITED STATES PATENT orrlce 2,143,914 COPPER- SILVER-BERYIJJUIVI-NICKEL ALLOY Franz R. Hensel and Earl I. Larsen, Indianapolis, Ind., assignors to P. R. Mallory & 00., Inc.,- Indianapolis, but, a corporation of Delaware No Drawing. Original application October 9,

1937, Serial No. 168,199. Divided and this application June 9, 1938,,Serial No. 212,686

Claims. (Cl. 75-159) An object of the invention is to produce an im- I proved copper base alloy.

Another object'is to improve copper-silver- 1Q beryllium alloys.

Other objects of the invention will be apparentfrom the following description taken in connection with the appended claims.

The present invention comprises the combination of elements, methods of manufacture, and the product thereof brought out and exemplified in thedisclosure hereinafter set forth, the scope of the invention being indicated in the appended claims.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the combination of elements without departing from the spirit of the invention.

- We are aware that work has been done on copper-silver-beryllium alloys. In most cases, however, the silver content was rather high and we are not aware of any prior art on silver contents below 5%. Silver is a rather expensive element and the alloys produced up to the present time have not found commercial use, because of their high cost. In our researches, we have discovered that considerably lower percentages of silver can be employed and that very excellent properties are obtained with such alloys.

Copper-silver alloys are susceptible to age hardening. This age hardening, however, is manifested more in improvements in electrical conductivity than in improvements in hardness. The hardness of alloys usually has to be obtained by cold working. Due to the fact that the copper-silver system is inherently an age hardening system, the annealing point of such cold worked alloys is fairly high. Silver, furthermore, has

the outstanding advantage that it will not decrease the electrical conductivity materially when alloyed with copper. This also is due to the very limited solid solubility of silver in copper.

We have found that at 600 degrees C., approximately 2.5% silver is held in solid solution, while at -200 degrees 0., only 0.3% of silver is held in solid'solution, and at room temperature, this solubility is still less. This indicates-definitely that 55 with small percents of silver, below 5% definite tern, an alloy can be produced which shows a effects can be obtained, as far as precipitation hardening is concerned.

By combining the eifects of age hardening of the copper-silver and the copper-beryllium sysvery high hardness obtained with the copperberyllium system, and an improved electrical conductivity, such as is obtained in the copper-silver system.

It is possible, for instance, to produce an alloy 10 containing 2' to 4% silver and 0.3 to 0.75% beryllium, which, after suitable heat treatment will show a conductivity of close to and a tensile strength of 95,000 p. s. i.

It is also possible to reduce the silver contents 15 to very low limits and obtain an improved alloy,

the improvement consisting not only in a higher electrical conductivity and in a higher age hardening temperature, but also in superior characteristics, in regard to corrosion resistance and 20 oxidation characteristics. The alloys are furthermore suitable for electrical contacting purposes, because they retain a comparatively low contact resistance.

We have found. that the addition of nickel to 25 the copper, silver and beryllium produces a marked improvement. The alloys thus produced may preferably contain the ingredients in the followin proportions:

P81 cent. 30 Berylli v 0.05 to 3 Silver ..'l.. 0.05 to 4 Nickel 0.05 to 10 Copper Balance.

Alloys of the type described may also contain 35 in some instances up to several percent of silicon, tin, zirconium, titanium, magnesium, zinc, cadmium, aluminum, calcium and lithium.

Within these composition ranges, there are a number of specific alloys which have been found 40 to be of particular importance. Two of the alloys are listed below:

I The alloys can be made according to standard alloying methods, such as melting the copper and adding the desired amounts oi silver and nickel.

Afterwards the correct amount of beryllium may be introduced in .the form of a copper-beryllium master alloy or any other form and the material can be cast either in a chill mould or in a sand mould, at the correct temperature.

After the alloy has been prepared according to standard alloying methods, the heat treatment may be carried out as follows:

'The alloy in the form of a billet or a sand casting or any desired form is raised in temperature to above 700 degrees C. and its melting point. The alloy is then quenched from this temperature and subsequently aged at temperatures at or below 600 degrees C. This heat treatment results in considerable improvements in the physical properties of the alloy. The alloy is particularly suitable for applications where high hardness and high electrical conductivity are required, and where physical properties have to be retained at elevated temperatures. The alloys have found further very extensive use in applications where the material is used for electrical contacting purposes, such as contactor contacts where arcs are drawn and surface oxidation produces high resistance films on ordinary copper alloys. I

The alloys are furthermore very suitable for springs, particularly springs which have to carry current or which have to withstand certain temperature rises without losing their elastic properties.

The alloys have-further found considerable use for wear resistance purposes and applications,

such as pressure welding electrodes and resist-a ance welding dies in general.

The material is also. suitable for special applications where' springs of intricate design must be formed in the soft condition; that is after quenching, and where a high hardness can be produces the desirable characteristics required for such applications.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. An alloy containing about 0.05 to 3% beryllium, 0.05 to 4% silver, 0.05 to .10% nickel and the balance copper.

2. An age-hardened alloy containing about 0.05 to 3% beryllium, 0.05 to 4% silver, 0.05 to 10% nickel, balance substantially all copper.

3. An alloy containing about 0.2 to 1% beryllium, 0.1 to 2.5% silver, 0.05 to 5% nickel and the balance copper.

4. An alloy containing about 1 to 2.5% beryllium, 0.1 to 2.5 silver, 0.05 to 5% nickel and the balance copper.

' 5. An electric contacting element of the type comprising pressure exerting welding electrodes and the like formed of an alloy containing about 0.05 to 3% beryllium, 0.05 to 4% silver, 0.05 to nickel and the balance copper.

FRANZ R. HENSEL. EARL I. LARSEN. 

